In the wake of the comments, Rosenberg wrote a staff memo on Saturday, obtained by CBS News, which refuted the 'roughing up' statement.

He said he didn't believe DEA agents would mistreat defendants, but wanted to make a 'strong reaffirmation of the operating principles to which we, as law enforcement professionals, adhere.'

He added he was writing 'because we have an obligation to speak out when something is wrong. That's what law enforcement officers do. That's what you do. We fix stuff. At least, we try,' he wrote.

He urged staff to keep to the agency's values of respect, integrity, and accountability.

President Donald Trump drew criticism from a 'joke' he made during a speech at Suffolk County Community College on Friday (pictured) in which he seemed to suggest it was acceptable to rough up suspects when arresting them

'This is how we conduct ourselves,' he wrote. 'This is how we treat those whom we encounter in our work: victims, witnesses, subjects, and defendants. This is who we are.'

Police departments across the country also hit out at Trump after the comments.

Speaking at the college in Brentwood, close to where the ultra-violent street gang MS-13 has committed a string of gruesome murders, he said: 'When you see these thugs being thrown into the back of a paddy wagon, you just seen them thrown in, rough. I said, "Please don't be too nice".

'Like when you guys put somebody in the car and you're protecting their head, you know, the way you put their hand over?' the president continued, mimicking the gesture. 'Like, don't hit their head and they've just killed somebody. Don't hit their head? I said, "You can take the hand away, OK?"'

The comment drew ire from several departments accusing Trump of normalizing police brutality.

The Suffolk County Police Department in New York was the first to hit back at Trump's remarks